The present invention relates to the installation of a fastener into a workpiece, such as, for example, a sheet metal panel and in particular, the installation of a fastener into a workpiece without piercing the workpiece.
Typically, fasteners are installed into a panel by piercing the panel with the fastener and plastically deforming the fastener and panel together. The assignee of the present invention has numerous patents to pierce type fasteners, methods for installing such fasteners, die buttons relating to such installation, heads for installing such fasteners, etc. Although pierce type fasteners are very effective in a wide variety of applications, there are some applications that do not benefit from their use. Another method of installing fasteners is by welding the fastener to the panel, a so-called weld nut. This method also poses problems in certain applications.
One example of a "non-pierce" a non-weld type installation is in a pan that is to retain a liquid. A specific example of such a "non-pierce" or non-weld application is the mounting of an air conditioner compressor to the condensation pan of an air conditioner. If the pan is pierced by a pierce type fastener, the pan has to be sealed at the pierce point. This can be done, for example, by using special fluid tight fasteners, separate sealing materials, coatings, etc. However, the use of these alternative methods can be relatively expensive and add to the overall cost of the assembly. With weld nuts, the same problem occurs because the weld nut must be placed in a pre-pierced hole for welding. Weld nuts have further disadvantages as well. They require a longer cycle time than either pierce or non-pierce fasteners, there is a spatter from the weld, heat from the weld can adversely effect the base metal and increase the potential for cracking, they are expensive and have toxicity problems when applied to galvanized materials.
Another "non-pierce" and non-weld type installation is in pre-painted or coated panels. With pre-painted or coated panels, the piercing operation can adversely effect the paint or coating, particularly at the pierce point. The piercing of the panel creates exposed metal that can rust and must be treated to prevent rusting. By using a "non-piercing" fastener, there is no exposed metal and the integrity of the paint or coating is not disturbed. Weld nuts cannot be welded to painted materials rendering them fairly useless unless the surface area is cleared of paint. This would be an expensive, time consuming process which would still have exposed surface area.